Add live mode detection in WebM MediaSource parser.

media/formats/webm/webm_stream_parser.cc

Index: media/formats/webm/webm_stream_parser.cc
diff --git a/media/formats/webm/webm_stream_parser.cc b/media/formats/webm/webm_stream_parser.cc
index 1a49c6694b2254953cbe05d52731c5240e3a2874..70530f884bc925510a8b274477af0c603e918ae1 100644
--- a/media/formats/webm/webm_stream_parser.cc
+++ b/media/formats/webm/webm_stream_parser.cc
@@ -18,8 +18,11 @@
 
 namespace media {
 
+static const int64 kUnknownElementSize = 0xffffffffffffff;
+
 WebMStreamParser::WebMStreamParser()
     : state_(kWaitingForInit),
+      unknown_segment_size_(false),
       parsing_cluster_(false) {
 }
 
@@ -150,6 +153,9 @@ int WebMStreamParser::ParseInfoAndTracks(const uint8* data, int size) {
       return result + element_size;
       break;
     case kWebMIdSegment:
+      // Segment of unknown size indicates live stream.
+      if (element_size == kUnknownElementSize)
+        unknown_segment_size_ = true;
       // Just consume the segment header.
       return result;
       break;
@@ -172,7 +178,11 @@ int WebMStreamParser::ParseInfoAndTracks(const uint8* data, int size) {
   cur_size -= result;
   bytes_parsed += result;
 
-  WebMTracksParser tracks_parser(log_cb_, ignore_text_tracks_);
+  bool live_mode = unknown_segment_size_ && (info_parser.duration() <= 0) &&
+                   !info_parser.date_utc().is_null();
+
+  WebMTracksParser tracks_parser(
+      log_cb_, ignore_text_tracks_, live_mode);
   result = tracks_parser.Parse(cur, cur_size);
 
   if (result <= 0)
@@ -203,7 +213,6 @@ int WebMStreamParser::ParseInfoAndTracks(const uint8* data, int size) {
     return -1;
   }
 
-
   cluster_parser_.reset(new WebMClusterParser(
       info_parser.timecode_scale(),
       tracks_parser.audio_track_num(),